Vertical distribution of the radon concentration at Batu Pahat district, Johor, Malaysia

Abstract

This study investigated the vertical distribution of radon, 222Rn concentrations in soil gas for different soil types and found the relation between the measured gamma dose rates and radon concentrations. The 222Rn concentrations in soil gas were measured at depth of 20 cm, 60 cm, 80 cm and 100 cm using semiconductor detector (RAD7) coupled with soil gas probe. The overall activity concentrations of 222Rnin soil were ranged from Minimum Detectable Activity (MDA)to 54000 ± 3000 Bq m−3 in Batu Pahat District. The results showed that the overall highest concentration of 222Rn was recorded at 40 cm depth for most of the soil types, which could be the most reliable for taking the radon measurements than other depths. Soil type 32 (Dystric Nitosolse Orthic Ferrasols-Rengam Jerangau) has the highest radon concentration, which was 12,462 ± 5237 Bq m-3. The gamma dose rates (GDR) above 1 m were measured using portable survey meters (Ludlum 19). A good relationship between radon concentrations in soil gas and the measured gamma dose rates was observed using Pearson Correlation. The results of 222Rn concentration in soil gas obtained from this study were in agreement with results reported by other researchers.